Transmission lines are used to transfer signals between portions of a circuit or system. Transmission lines are often used in radio frequency (RF) circuits. In some approaches, a pair of transmission lines called differential transmission lines are used to transfer signals between separate portions of the circuit or system. As technology nodes for circuits decrease, spacing between adjacent transmission lines decreases.
Unlike conductive lines in an interconnect structure, transmission lines are used to carry signals having alternating current (AC) signals. A length of transmission lines is sufficiently long that a wave nature of the transferred signal impacts performance of the transmission line. In contrast, conductive lines in interconnect structures are often formed without consideration for a wave nature of a signal along the conductive line.